1. Technical Field
The present invention relates to a method of recording media data on a storage medium and a method and system for accessing the media data recorded on the storage medium. Particularly, the invention relates to embedding management information into media data and controlling access to the data, based on this management information, when the data is accessed.
2. Prior Art
With the spread of multimedia environments, systems handling digital information, such as digital video disks (DVDs), digital video cameras (DVCs), digital CS satellite broadcasting, and internets, are becoming still more popular. Also, the development of apparatuses which can process and transfer very large quantities of multimedia data at high speed has advanced. However, continued and further increase in popularity of such devices depends upon the number of applications, such as theater movies. No matter how excellent hardware may be, the spread of the hardware would be difficult it there is a small quantity of software which attracts the purchasing desire of customers.
What is problematic at this time is the protection of works or contents stored on various medium. For example, digital video disks have a sufficient hardware based method in the distribution of theater movies. However, for addressing problems with protection of copyright or prevention of illegal copy, there have been no methods provided that are satisfactory to suppliers of works or contents. This is because the contents of digital data can be easily copied and changed. Under such present conditions, it cannot be expected that many attractive contents are distributed with these media. In fact, since such problems with copyright have not been solved, digital video cameras have only been sold as exclusive machines for photographing.
Thus, effectively protecting digitized works is indispensable for a further spread of multimedia, and the development of such protection techniques and the generation of normalized standards have been pursued.
When the duplication conditions of digital contents of digital audio tape (DAT), are controlled, a copy generation management system (CGMS) signal has hitherto been adopted generally. The CGMS signal is constituted by two bits of data and represents the following duplication.
______________________________________ CGMS Signal Duplication Condition ______________________________________ 11 Duplication inhibition 00 No limitations on duplication 10 One-time duplicability ______________________________________
The aforementioned method writes the two data bits in a predetermined place of data format. When duplication is performed, the aforementioned CGMS signal is detected at a receiver end. If the content of the signal represents duplication inhibition, the receiver stops the duplication of the content. However, this written place can be easily detected and the content can also be easily written over, so it is easy for users to overwrite the content of this signal. That is, it is difficult in the conventional technique to effectively prevent the illegal duplication of contents. Hence, there has been a desire for the development of techniques which can effectively manage access to digital contents and effectively prevent illegal duplication.